Skip to content

NetworkManager Network configuration tool suite

In 2004, Red Hat launched the NetworkManager project, which aims to make it easier for Linux users to meet the needs of current network management, especially the management of wireless networks. Today, the project is managed by GNOME. The homepage of the website is:

Official introduction - NetworkManager is a standard Linux network configuration tool suite. It supports various network settings from desktop to server and mobile devices, and is perfectly integrated with popular desktop environments and server configuration management tools.

The suite mainly includes two command line tools:

  • nmtui. Configure the network in a graphical interface.
shell > dnf -y install NetworkManager NetworkManager-tui
shell > nmtui
NetworkManager TUI
Edit a connection
Activate a connection
Set system hostname
  • nmcli. Use the command line to configure the network, either a pure command line or an interactive command line.
Shell > nmcli connection show                                                                                                        
NAME    UUID                                  TYPE      DEVICE                                                                              
ens160  25106d13-ba04-37a8-8eb9-64daa05168c9  ethernet  ens160

For RockyLinux 8.x, we introduced how to configure its network here. You can use vim to edit the network card configuration file in the /etc/sysconfig/network-script/ directory, or you can use nmcli/nmtui, both of which are acceptable.

Naming rules for udev device Manager

For RockyLinux 9.x, if you go to the /etc/sysconfig/network-scripts/ directory, there will be a readme-ifcfg-rh.txt description text that prompts you to go to the /etc/NetworkManager/system-connections/ directory.

Shell > cd /etc/NetworkManager/system-connections/  && ls 

The ens160 here refers to the name of the network card in the system. You may wonder why the name looks so strange? This is because of the udev device manager. It supports many different naming schemes. By default, fixed names are assigned according to firmware, topology, and location information. Its advantages include:

  • Device names are fully predictable.
  • Device names stay fixed even if you add or remove hardware, because no re-enumeration takes place.
  • Defective hardware can be seamlessly replaced.

In RHEL 9 and the corresponding community version operating systems, consistent device naming is enabled by default. The udev device manager will generate device names according to the following scheme:

Scheme Description Example
1 Device names incorporate firmware or BIOS-provided index numbers for onboard devices. If this information is not available or applicable, udev uses scheme 2. eno1
2 Device names incorporate firmware or BIOS-provided PCI Express (PCIe) hot plug slot index numbers. If this information is not available or applicable, udev uses scheme 3. ens1
3 Device names incorporate the physical location of the connector of the hardware. If this information is not available or applicable, udev uses scheme 5. enp2s0
4 Device names incorporate the MAC address. Red Hat Enterprise Linux does not use this scheme by default, but administrators can optionally use it. enx525400d5e0fb
5 The traditional unpredictable kernel naming scheme. If udev cannot apply any of the other schemes, the device manager uses this scheme. eth0

udev device Manager names the prefix of the NIC based on the type of interface:

  • en for Ethernet.
  • wl for wireless LAN (WLAN).
  • ww for wireless wide area network (WWAN).
  • ib, InfiniBand network.
  • sl, Serial Line Internet Protocol (slip)

Add some suffixes to the prefix, such as:

  • o on-board_index_number
  • s hot_plug_slot_index_number [f] function [d] device_id
  • x MAC_address
  • [P] domain number p bus s slot [f] function [d] device_id
  • [P] domain number p buss s slot [f] function [u] usb port [c] config [i] interface

You can use man 7 to get more detailed information.

Users can not only configure the network in a pure command line mode, but also use interactive commands to configure the network.

nmcli connection

The nmcli connection command can show, delete, add, modify, edit, up, down, and so on.

For specific usage, please refer to nmcli connection add --help, nmcli connection edit --help, nmcli connection modify --help and so on.

For example, to configure a new ipv4 static ip connection using a pure command line and start up automatically, it can be:

Shell > nmcli  connection  add  type  ethernet  con-name   CONNECTION_NAME  ifname  NIC_DEVICE_NAME   \
ipv4.method  manual  ipv4.address ""  ipv4.gateway ""  ipv4.dns "," \
ipv6.method  disabled  autoconnect yes

If you are using DHCP to get the ipv4 address, it can be:

Shell > nmcli  connection  add  type ethernet con-name CONNECTION_NAME  ifname  NIC_DEVICE_NAME \
ipv4.method  auto  ipv6.method  disabled  autoconnect  yes

With the above configuration, the connection is not activated. You need to perform the following operations:

Shell > nmcli connection up  NIC_DEVICE_NAME

Enter the interactive interface through the edit keyword on the basis of the existing connection, and modify it:

Shell > nmcli connection  edit  CONNECTION_NAME
nmcli > help

You can also modify one or more properties of the connection directly from the command line with the modify keyword. For example:

Shell > nmcli connection modify CONNECTION_NAME autoconnect yes ipv6.method dhcp


Operations through nmcli or nmtui are saved permanently, not temporarily.

Some use multiple network cards for link aggregation. In the early days, using bonding technology, there were seven working modes (0~6), and the bond mode only supported two network cards at most; Later, the teaming technology is gradually used as an alternative, there are five working modes, and the team mode can use up to eight network cards. Comparison link between bonding and teaming——

For example, the 0 mode of bonding:

Shell > nmcli  connection  add  type  bond  con-name  BOND_CONNECTION_NAME   ifname  BOND_NIC_DEVICE_NAME  mode 0  
Shell > nmcli  connection  add  type  bond-slave   ifname NIC_DEVICE_NAME1   master  BOND_NIC_DEVICE_NAME
Shell > nmcli  connection  add  type  bond-slave   ifname NIC_DEVICE_NAME2   master  BOND_NIC_DEVICE_NAME

You can view more detailed information through man 5 NetworkManager.conf and man 5 nm-settings-nmcli.

The content of the configuration file of the NetwrokManager network card is an init-style key file. For example:

Shell > cat /etc/NetworkManager/system-connections/ens160.nmconnection                                                               




  • Lines that start with # and blank lines are considered comments;
  • Enclosed in [ and ] is the section it intends to declare the title, and below it are the specific key-value pairs contained. Each declared title and its key-value pair form a syntax segment;
  • Any file with the .nmconnection suffix can be used by NetworkManager.

connection title names can contain these common key-value pairs:

key name description
id The alias of con-name, whose value is a string.
uuid Universal unique identifier, whose value is a string.
type The type of connection, whose values can be ethernet, bluetooth, vpn, vlan, and so on. You can use man nmcli to view all supported types.
interface-name Network card device name.
timestamp Unix timestamp, in seconds. The value here is the number of seconds since January 1, 1970.
autoconnect Whether it starts automatically when the system starts. The value is of Boolean type.

ethernet title names can contain these common key-value pairs:

key name description
mac-address MAC physical address.
mtu Maximum Transmission Unit.
auto-negotiate Whether to negotiate automatically. The value is Boolean type.
duplex The Values can be half (half-duplex), full (full-duplex)
speed Specify the transmission rate of the network card. 100 is 100Mbit/s. If auto-negotiate=false, the speed key and duplex key must be set; if auto-negotiate=true, the speed used is the negotiated speed, and the writing here does not take effect (this is only applicable to the BASE-T 802.3 specification); when nonzero, the duplex key must have a value.

ipv4 title names can contain these common key-value pairs:

key name description
method The method to be obtained by ip. The value is of string type. The value can be: auto, disabled, link-local, manual, shared

Last update: January 18, 2023

Author: tianci li

Contributors: Steven Spencer